Stimulus-Dependent Interaction between the Visual Areas 17 and 18 of the 2 Hemispheres of the Ferret (Mustela putorius)

Abstract

To study how the visual areas of the 2 hemispheres interact in processing visual stimuli we have recorded local field potentials in the callosally connected parts of areas 17 and 18 of the ferret during the presentation of 3 kinds of stimuli: 2.5 degrees squares flashed for 50 ms randomly in the visual field (S1), 4 full-field gratings differing in orientation by 45 degrees and identical in the 2 hemifields (S2) and gratings as above but whose orientation and/or direction of motion differed by 90 degrees in the 2 hemifields (S3). The gratings remained stationary for 0.5 s and then moved in 1 of the 2 directions perpendicular to their orientation for 3 s. We compared the responses in baseline conditions with those obtained whereas the contralateral visual areas were inactivated by cooling. Cooling did not affect the responses to S1 but it modified those to S2 and to S3 generally increasing early components of the response while decreasing later components. These findings indicate that interhemispheric processing is restricted to visual stimuli which achieve spatial summation and that it involves complex inhibitory and facilitatory effects, possibly carried out by interhemispheric pathways of different conduction velocity.

Evolution amplified processing with temporally dispersed slow neuronal connectivity in primates

“…4). The network consists of 2 couples of symmetrically connected excitatory and inhibitory Hindmarsch-Rose type neurons with faster excitatory-to-inhibitory connections and slower excitatory-to-excitatory connections, compatible with recent electrophysiological data in the ferret visual system (16). When the neurons are set in a bursting/oscillatory mode, the network generates bursts consisting of excitation curtailed by inhibition.…”

“…This system exhibits bursting behavior (a ϭ 2.6 and I ϭ 4). The network consisted of 2 excitatory neurons (E1 and E1Ј) and 2 inhibitory neurons (I2 and I2Ј) connected, as suggested, by experimental findings (16). To model the interactions between connected neurons, we add a coupling term to the x variable of each neuron, which is an activation function of the sum of output of afferent neurons:…”

Cell Diversity and Connection Specificity between Callosal Projection Neurons in the Frontal Cortex

“…In contrast, excitation from callosal inputs would facilitate information integration and cooperation between hemispheres. Moreover, in the visual cortex, interhemispheric callosal inputs modulate specific visual responses where inhibitory and excitatory effects are involved (Makarov et al, 2008;Nakamura et al, 2008;Schmidt et al, 2010). Consistent with these bidirectional effects, callosal fibers innervate both excitatory cells and inhibitory interneurons (Kawaguchi, 1992;Carr and Sesack, 1998;Karayannis et al, 2007;Petreanu et al, 2007).…”

Visual callosal connections: role in visual processing in health and disease

“…Specifically, Makarov et al (2008) performed recordings of LFPs triggered by visual stimulation in one side before and after reversible inactivation by cooling of the contralateral hemisphere in ferrets. The authors report both increases and decreases of visual responses following cooling.…”